Fox has joined the cast of the upcoming live-action, CGI hybrid Teenage Mutant Ninja Turtles reboot that Bay is producing for Paramount.

The director took to his website to announce the news: "TMNT: We are bringing Megan Fox back into the family."

Fox, 26, famously fell out with Bay during the filming of the Transformers franchise. The actress appeared in Bay's first two Transformers movies, released in 2007 and 2009, but was replaced with model-turned-actress Rosie Huntington-Whiteley in the third installment, 2011's Transformers: Dark of the Moon.

It's my first real movie and it's not honest and not realistic. The movie wasn't bad, I just wasn't proud about what I did."

Later that year, Fox hit the headlines again after she compared Bay to Hitler in a magazine interview.

She said of Bay in Wonderland magazine: "He's like Napoleon and he wants to create this insane, infamous mad-man reputation. He wants to be like Hitler on his sets, and he is. So he's a nightmare to work for, but when you get him away from set, and he's not in director mode, I kind of really enjoy his personality because he's so hopelessly awkward."

Adding, "He has no social skills at all. And it's endearing to watch him."

The actress was subsequently trashed by three anonymous members of the Transformers crew who published an open letter to her on Bay's website.

They branded her "dumb as a rock" and the "queen of talking trailer trash and posing like a porn star," as well as "grumpy" and "thankless, classless, graceless."

Bay later said that producer Steven Spielberg had ordered him to fire Fox over "you know, the Hitler thing".

He also said he wasn't hurt" by Fox's swipe. "Because I know that's just Megan. Megan loves to get a response. And she does it in kind of the wrong way. I'm sorry, Megan. I'm sorry I made you work 12 hours. I'm sorry that I'm making you show up on time. Movies are not always warm and fuzzy."

Bay did not say what role Fox would play in the Ninja Turtles reboot, but per The Hollywood Reporter, Fox will star as April O'Neil, a reporter and the crime-fighting turtles' human friend.

According to Reuters, Fox's agent has since confirmed that she's been cast in that particular role.

The Ninja Turtles movie is currently in the casting stage, THR notes, with turtles Donatello, Michelangelo, Leonardo and Raphael expected to be played by "relative unknowns", who will appear on the big screen via motion-capture techniques.

Speaking at the annual Nickelodeon Upfront event in New York, Bay revealed plans to recast the crime-fighting superheroes as aliens.

"When you see this movie, kids are going to believe, one day, that these turtles actually do exist when we are done with this movie," Bay said during a presentation.

"These turtles are from an alien race, and they are going to be tough, edgy, funny and completely loveable."

The original back-story goes that the four turtles - Leonardo, Raphael, Michelangelo and Donatello - mutated into masked, pizza-loving crime-fighters after they were exposed to radioactive ooze in the New York sewers.

"Fans need to take a breath, and chill. They have not read the script," he wrote.

"Our team is working closely with one of the original creators of Ninja Turtles to help expand and give a more complex back story. Relax, we are including everything that made you become fans in the first place. We are just building a richer world."

He was forced to speak out again in September 2012, when the internet was abuzz with the apparent leak of a first draft of the script for the movie.

"The leaked script for Ninja Turtles that different sites continue to comment on was written well before I, or anyone at Platinum Dunes, was involved with the project," Bay wrote.

"That script saw the shredder a long time ago. This is tired, old news - wait for the movie!"

Directed by Jonthan Liebesman (Wrath of the Titans), the film is set for release in May 2014.